Study may help understand antimatter

Korea University researchers have collided matter and antimatter particles in a study that could provide essential information on why antimatter is almost nonexistent.

Using a linear particle accelerator, researchers smashed an electron into a positron ― the antimatter version of an electron ― at nearly the speed of light, producing a type of subatomic particle called a charm quark meson. This charm quark meson is made up of two smaller particles ― a “charm” quark and an “up” antiquark ― and exists for 10-trillionths of a second.

This graph shows how an electron (e-) collides with positron (e+) to form a charm quark meson.

Researchers said the results showed that quantum states changed 99.9999 percent of the time.

“While past studies have induced the quantum state such as in proton collision experiments, no one else had proved that this was possible in an electron-positron collision,” said Ko Byeong-rok, lead researcher of the Elementary Particle Physics Lab at Korea University.

It is believed that in the beginning stages of the universe, matter and antimatter existed in equal amounts. Scientists have worked to find out why the universe today is nearly entirely made of regular matter.

“This is the ultimate question. Our study certainly did not provide the answer, but it is a huge step forward,” said Won Eun-il, a professor of physics at Korea University and corresponding researcher of the study.

He said the environment in which both matter and antimatter existed is believed to have involved an extremely high temperature and amount of energy.

“In order to understand how matter and antimatter came to existence, we need (to create) a similar environment,” he said, explaining why a particle collider was used.

The study hints at matter-antimatter asymmetry by demonstrating particle-antiparticle asymmetry that was induced by the mixing of quantum states. While the results are promising, they only provide limited clues to understanding antimatter because the experiment was carried out under specific circumstances. Other conditions may produce different results.

But the scientists expressed hope that the study would lay the foundation for subsequent research on antimatter.

The study is also expected to aid research on the Higgs Boson, an elementary particle that was discovered in 2012.

“Research on Higgs must be conducted on an electron-positron basis, just like our study. Our techniques can be applied to the Higgs’ study,” said Ko.

The study was published in the March 21 edition of scientific journal Physical Review Letters.